“Unable to resolve host Ubuntu server” – Troubleshooting Guide for Devs

Hey Dev, are you facing the annoying “unable to resolve host” error while working on your Ubuntu server? We know how frustrating it can be when you are in the middle of an important task, and the error pops up out of nowhere. But don’t worry, we’ve got your back! In this article, we will guide you through the troubleshooting process to fix the error and get back to work smoothly.

Understanding the “Unable to resolve host Ubuntu server” error

Before jumping into the solutions, it’s crucial to understand what causes the “unable to resolve host” error. In simple words, the error means that your server is unable to find the hostname you are trying to access. It can occur due to various reasons, such as DNS resolution failure, incorrect hostname configuration, or firewall restrictions.

Now that you know the cause let’s move forward with the solutions.

Solution 1: Check your DNS settings

DNS (Domain Name System) is responsible for translating domain names into IP addresses. A misconfigured DNS server or incorrect DNS settings can lead to the “unable to resolve host” error. Here’s how you can check your DNS settings:

Commands	Description
sudo nano /etc/resolv.conf	Open the resolv.conf file in the nano editor
nameserver 8.8.8.8	Add Google DNS server address
nameserver 8.8.4.4	Add another Google DNS server address
sudo service networking restart	Restart the network service

After applying these commands, try accessing the hostname again, and the error should be resolved.

Solution 2: Verify hostname configuration

Incorrect hostname configuration can lead to the “unable to resolve host” error. Here are the steps to verify and configure the hostname:

1. Check the current hostname by running the command “hostname”.
2. Verify the hostname in the “/etc/hostname” file.
3. Edit the host file using “sudo nano /etc/hosts” command and add the hostname and IP address in the correct format.
4. Save the file and restart the networking service using “sudo service networking restart”.

After completing these steps, the error should be resolved.

Solution 3: Check Firewall restrictions

Firewall restrictions can also cause the “unable to resolve host” error. Here are the steps to check and modify firewall settings:

1. Check if the firewall is active using the command “sudo ufw status”.
2. If the firewall is active, allow the required ports and protocols for the services you are trying to access using the command “sudo ufw allow port/protocol”.
3. Verify the changes by running the command “sudo ufw status”.
4. Restart the networking service using the “sudo service networking restart” command.

After applying these changes, the error should be resolved.

FAQ about “Unable to resolve host Ubuntu server”

Q. What is the default DNS server in Ubuntu?

A. The default DNS server in Ubuntu is 127.0.0.53.

Q. How do I restart the DNS service in Ubuntu?

A. You can restart the DNS service in Ubuntu by running the command “sudo systemctl restart systemd-resolved.service”.

Q. What is the correct format for the hostname configuration file?

A. The correct format for the hostname configuration file is “hostname.domainname”. For example, “server.example.com”.

Q. Can I disable the firewall in Ubuntu?

A. It’s not recommended to disable the firewall in Ubuntu. However, if you want to disable it, you can use the command “sudo ufw disable”.

Q. How do I check the status of the firewall in Ubuntu?

A. You can check the status of the firewall in Ubuntu by running the command “sudo ufw status”.

So, Dev, these were the solutions to fix the “unable to resolve host” error in Ubuntu server. We hope this article helped you in resolving the issue and saving your time. If you have any queries or suggestions, feel free to drop them in the comments below. Happy coding!